/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package org.dom4j;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

import org.dom4j.tree.QNameCache;
import org.dom4j.util.SingletonStrategy;

/**
 * <p> <code>QName</code> represents a qualified name value of an XML element
 * or attribute. It consists of a local name and a {@link Namespace}instance.
 * This object is immutable. </p>
 * 
 * @author <a href="mailto:jstrachan@apache.org">James Strachan </a>
 */
public class QName implements Serializable
{
   /** The Singleton instance */
   private static SingletonStrategy singleton = null;

   static
   {
      try
      {
         String defaultSingletonClass = "org.dom4j.util.SimpleSingleton";
         Class clazz = null;
         try
         {
            String singletonClass = defaultSingletonClass;
            singletonClass =
               System.getProperty("org.dom4j.QName.singleton.strategy",
                  singletonClass);
            clazz = Class.forName(singletonClass);
         }
         catch(Exception exc1)
         {
            try
            {
               String singletonClass = defaultSingletonClass;
               clazz = Class.forName(singletonClass);
            }
            catch(Exception exc2)
            {
            }
         }
         singleton = (SingletonStrategy) clazz.newInstance();
         singleton.setSingletonClassName(QNameCache.class.getName());
      }
      catch(Exception exc3)
      {
      }
   }

   /** The local name of the element or attribute */
   private String name;

   /** The qualified name of the element or attribute */
   private String qualifiedName;

   /** The Namespace of this element or attribute */
   private transient Namespace namespace;

   /** A cached version of the hashcode for efficiency */
   private int hashCode;

   /** The document factory used for this QName if specified or null */
   private DocumentFactory documentFactory;

   public QName(String name)
   {
      this(name, Namespace.NO_NAMESPACE);
   }

   public QName(String name, Namespace namespace)
   {
      this.name = (name == null) ? "" : name;
      this.namespace = (namespace == null) ? Namespace.NO_NAMESPACE : namespace;
   }

   public QName(String name, Namespace namespace, String qualifiedName)
   {
      this.name = (name == null) ? "" : name;
      this.qualifiedName = qualifiedName;
      this.namespace = (namespace == null) ? Namespace.NO_NAMESPACE : namespace;
   }

   public static QName get(String name)
   {
      return getCache().get(name);
   }

   public static QName get(String name, Namespace namespace)
   {
      return getCache().get(name, namespace);
   }

   public static QName get(String name, String prefix, String uri)
   {
      if(((prefix == null) || (prefix.length() == 0)) && (uri == null))
      {
         return QName.get(name);
      }
      else if((prefix == null) || (prefix.length() == 0))
      {
         return getCache().get(name, Namespace.get(uri));
      }
      else if(uri == null)
      {
         return QName.get(name);
      }
      else
      {
         return getCache().get(name, Namespace.get(prefix, uri));
      }
   }

   public static QName get(String qualifiedName, String uri)
   {
      if(uri == null)
      {
         return getCache().get(qualifiedName);
      }
      else
      {
         return getCache().get(qualifiedName, uri);
      }
   }

   public static QName get(String localName, Namespace namespace,
      String qualifiedName)
   {
      return getCache().get(localName, namespace, qualifiedName);
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the local name
    */
   public String getName()
   {
      return name;
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the qualified name in the format <code>prefix:localName</code>
    */
   public String getQualifiedName()
   {
      if(qualifiedName == null)
      {
         String prefix = getNamespacePrefix();

         if((prefix != null) && (prefix.length() > 0))
         {
            qualifiedName = prefix + ":" + name;
         }
         else
         {
            qualifiedName = name;
         }
      }

      return qualifiedName;
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the namespace of this QName
    */
   public Namespace getNamespace()
   {
      return namespace;
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the namespace URI of this QName
    */
   public String getNamespacePrefix()
   {
      if(namespace == null)
      {
         return "";
      }

      return namespace.getPrefix();
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the namespace URI of this QName
    */
   public String getNamespaceURI()
   {
      if(namespace == null)
      {
         return "";
      }

      return namespace.getURI();
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the hash code based on the qualified name and the URI of the
    *         namespace.
    */
   public int hashCode()
   {
      if(hashCode == 0)
      {
         hashCode = getName().hashCode() ^ getNamespaceURI().hashCode();

         if(hashCode == 0)
         {
            hashCode = 0xbabe;
         }
      }

      return hashCode;
   }

   public boolean equals(Object object)
   {
      if(this == object)
      {
         return true;
      }
      else if(object instanceof QName)
      {
         QName that = (QName) object;

         // we cache hash codes so this should be quick
         if(hashCode() == that.hashCode())
         {
            return getName().equals(that.getName())
               && getNamespaceURI().equals(that.getNamespaceURI());
         }
      }

      return false;
   }

   public String toString()
   {
      return super.toString() + " [name: " + getName() + " namespace: \""
         + getNamespace() + "\"]";
   }

   /**
    * DOCUMENT ME!
    * 
    * @return the factory that should be used for Elements of this QName
    */
   public DocumentFactory getDocumentFactory()
   {
      return documentFactory;
   }

   public void setDocumentFactory(DocumentFactory documentFactory)
   {
      this.documentFactory = documentFactory;
   }

   private void writeObject(ObjectOutputStream out) throws IOException
   {
      // We use writeObject() and not writeUTF() to minimize space
      // This allows for writing pointers to already written strings
      out.writeObject(namespace.getPrefix());
      out.writeObject(namespace.getURI());

      out.defaultWriteObject();
   }

   private void readObject(ObjectInputStream in) throws IOException,
      ClassNotFoundException
   {
      String prefix = (String) in.readObject();
      String uri = (String) in.readObject();

      in.defaultReadObject();

      namespace = Namespace.get(prefix, uri);
   }

   private static QNameCache getCache()
   {
      QNameCache cache = (QNameCache) singleton.instance();
      return cache;
   }
}

/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived
 * from this Software without prior written permission of MetaStuff, Ltd. For
 * written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may
 * "DOM4J" appear in their names without prior written permission of MetaStuff,
 * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */